PURGE COMPOSITION AND METHOD

BACKGROUND OF THE INVENTION

THIS invention relates to purge compositions for use in plastic extrusion and to a method of purging a plastic extruder or injection moulder.

A whole myriad of plastics exist today with differing properties. These plastics can be further tailored to meet specific requirements by alloying or addition of additives. These materials are called thermoplastics, on account of the fact that they can be moulded or shaped by heating, generally in an extruder or moulder.

In the extrusion process, plastic materials are fed in powder or granular form to an extruder, where they are typically heated to between 150 and 300 ⁰ C in order to soften or melt the plastic. The plastic can then be moulded or formed into the desired article. At the end of the production process, the extruder is cooled and cleaned. Depending on the circumstances this can take place daily, weekly or at longer intervals. It is normal practice to purge the extruder of any heat sensitive materials before cleaning. Purge compounds, used for this purpose, contain a plastic and other additives (abrasives, detergents) designed to remove any residual materials which may have built up on the walls of the extruder, along with heat stabilizers to prevent or minimise burning of the purge composition itself.

PVC is a plastic that is especially sensitive to thermal degradation. When exposed to heat for a prolonged period, it discolours and decomposes with the evolution of hydrogen chloride, it also becomes brittle in the process as a result of crosslinking of the polymer chains. In the past it has been necessary to purge PVC extruders with a purge composition based on a different plastic which is less heat sensitive. This resulted in further problems such as extended purging times, inefficient purging, plateing out etc., due to the incompatibility of the other plastic with PVC.

Previously, PVC has been stabilised by the addition of various metallic compositions based on for example, tin, lead, barium, zinc etc. These compositions are designed to scavenge the evolved hydrogen chloride. Depending on the addition level they will protect the PVC for a period, but ultimately fail, leading to decomposition of the PVC in the extruder in the normal manner. Thus, PVC compositions stabilised with metallic compositions are not suitable for purging purposes.

It is an object of this invention to provide a purge composition and method that can withstand the effects of heat for a prolonged period and is compatible with PVC.

SUMMARY OF THE INVENTION

According to a first aspect of the invention there is provided a polymer purge composition, typically based on PVC, wherein the purge composition is stabilized with an organic based stabilizer (OBS).

The OBS may include a compound of the Formula 1 :

wherein:

Y is O or S, preferably O; and

R ₁ , R ₂ , and R ₃ are monovalent substituents selected from the group consisting of hydrogen, halogen, hydroxyl, alkyl, aryl, aralkyl, acyl, amino, aminoalkyl, aminoaryl, and hydrazino.

The organic based stabiliser is preferably a combination of A) at least one compound of Formula I:

wherein:

R ₃ Js NH ₂ ,

R ₁ and R ₂ are each independently of the other C ₁ -C ₁₂ alkyl, C ₃ -C ₆ alkenyl, C ₅ -C ₈ cycloalkyl that is unsubstituted or substituted by from 1 to 3 C ₁ -C ₄ alkyl, C ₁ -C ₄ alkoxy, C ₅ -C ₈ cycloalkyl or by hydroxy groups or by chlorine atoms, or C ₇ -C ₉ phenylalkyl that is unsubstituted or substituted at the phenyl ring from 1 to 3 C ₁ -C ₄ alkyl, C ₁ -C ₄ alkoxy, C ₅ -C ₈ cycloalkyl or by hydroxy groups or chlorine atoms, and R^ and R* ₂ may additionally be hydrogen and C ₁ -C ₁₂ alkyl, and Y is S or O;

and B) at least one compound selected from the group consisting of perchlorate compounds, glycidil compounds, beta-diketones and beta-keto esters, dihydropyridines and polydihydropyridines, polyols and disaccharide alcohols, sterically hindered amines (tetraa lkylpiperidine compounds), alkali aluminosilicates, hydrotalcites and alkali aluminocarbonates (dawsonites), alkali(or alkaline earth-) carboxylates, -(bi)carbonates or hydroxides, antioxidants, lubricants or organotin compounds which are suitable for stabilising chlorine-containing polymers, especially PVC.

The purge composition preferably includes an abrasive filler/s and detergent/s or lubricant/s.

Typically the purge composition contains 5 to 15%, preferably 6 to 10% by mass of the OBS.

The invention also relates to a concentrate composition for inclusion with a purge composition, the concentrate containing an abrasive filler, an OBS and a detergent/lubricant.

Typically, the concentrate composition contains 50 to 80% by mass abrasive filler, 15 to 40%, typically 15 to 35%, by mass OBS and 2 to 10 % by mass detergent/lubricant.

According to a second aspect of the invention there is provided a method of purging an extruder in a polymer, typically a PVC, extrusion process, wherein a polymer purge composition that is stabilized with OBS is used.

In the method of the invention at the end of a polymer extrusion process, which takes place at a temperature typically between 150 and 300 ⁰ C in an extruder or injection moulder which includes a barrel which feeds molten polymer to a die, a polymer purge composition containing an OBS is fed into the extruder and is expelled from the die.

In the event the polymer purge composition is required to remove hard decomposed deposits extrusion with the purge composition continues until such time as the polymer material expelled from the die is clean and free of decomposed matter.

The die may then removed and allowed to cool for storage until next required.

The heaters on the barrel may be switched off; and the extruder allowed to cool with the polymer purge composition remaining in the barrel.

In the event that the barrel is to be further cleaned or a screw replaced in the barrel, extrusion may continue until such time as the extruder temperature is low enough that the polymer purge composition exits the end of the barrel as a powder, thus facilitating easier removal and cleaning.

Typical OBS's and purge compositions used in the method of purging an extruder are described above.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a graph of temperature versus time in a Brabender Temperature/Torque Test carried out on a PVC composition stabilized with a metallic based stabilizer; and

Figure 2 is a graph of temperature versus time in a Brabender Temperature/Torque Test carried out on a PVC composition stabilized with a organic based stabilizer.

DESCRIPTION OF PREFERRED EMBODIMENTS

According to the invention there is provided a purge composition for use in the purging of an extruder in the plastic extrusion process.

The purge composition consists of a plastic, preferably polyvinyl chloride (PVC), abrasives and detergents or lubricants, and is stabilized with an Organic Based Stabiliser (OBS) typically based on uracils.

The OBS may include a compound of the Formula 1 :

wherein Y is O or S, preferably O, and R ₁ , R ₂ , and R ₃ are monovalent substituents selected from the group consisting of hydrogen, halogen, hydroxyl, alkyl, aryl, aralkyl, acyl, amino, aminoalkyl, aminoaryl, and hydrazino. These compounds are described in more detail in US 3,436,362, the content of which is incorporated herein by reference.

The OBS used in this invention is preferably that described in US 5,925,969 (the content of which is incorporated herein by reference). A description of the OBS, from the specification of US 5,925,969 is provided below:

The OBS is preferably a combination of A) at least one compound of Formula 1:

wherein: R ₃ is NH ₂

R ₁ and R ₂ are each independently of the other C ₁ -C ₁₂ alkyl, C ₃ -C ₆ alkenyl, C ₅ -C ₈ cycloalkyl that is unsubstituted or substituted by from 1 to 3 C ₁ -C ₄ alkyl, C ₁ -C ₄ alkoxy, C ₅ -C ₈ cycloalkyl or by hydroxy groups or by chlorine atoms, or C ₇ -Cg phenylalkyl that is unsubstituted or substituted at the phenyl ring from 1 to 3 C ₁ -C ₄ alkyl, C ₁ -C ₄ alkoxy, C ₅ -C ₈ cycloalkyl or by hydroxy groups or chlorine atoms, and FV ₁ and R ^* ₂ may additionally be hydrogen and C ₁ -C ₁₂ alkyl, and Y is S or O;

and B) at least one compound selected from the group consisting of perchlorate compounds glycidil compounds, beta-diketones and beta-keto esters, dihydropyridines and polydihydropyridines, polyols and disaccharide alcohols, sterically hindered amines (tetraalkylpiperidine compounds), alkali aluminosilicates, hydrotalcites and alkali aluminocarbonates (dawsonites), alkali(or alkaline earth-) carboxylates, -(bi)carbonates or hydroxides, antioxidants, lubricants or organotin compounds which are suitable for stabilising chlorine-containing polymers, especially PVC.

For compounds of Formula 1 :

C ₁ -C ₄ Alkyl is, for example: methyl, ethyl, n-propyl, isopropyl, n-, iso-, sec- or tert-butyl.

C- _I -C ₁₂ Alkyl is, for example, in addition to the radicals just mentioned, pentyl, hexyl, heptyl, octyl, 2-ethylhexyl, isooctyl, decyl, nonyl, undecyl or dodecyl.

C ₁ -C ₄ Alkoxy is, for example, methoxy, ethoxy, propoxy, isopropoxy, butoxy or isobutoxy.

C ₅ -C ₈ Cycloalkyl is, for example, cyclopentyl, cyclohexyl, cycloheptyl or cyclooctyl.

C ₇ -C ₉ Phenylalkyl is, for example, benzyl, 1- or 2-phenylethyl, 3- phenylpropyl, a,a-dimethylbenzyl or 2-phenylisopropyl, preferably benzyl.

When the cycloalkyl groups or the phenyl group of the phenylalkyl radicals are substituted, then they are substituted preferably by two or one substituents and, of the substituents, especially by Cl, hydroxy, methyl or methoxy. C ₃ -C ₆ Alkenyl is, for example, vinyl, allyl, methallyl, 1-butenyl or 1-hexenyl, preferably allyl.

Preference is given to compounds of Formula I wherein Ri and R ₂ are each independently of the other C ₁ -C ₄ alkyl and hydrogen. Especially preferably, either R ₁ and R ₂ are identical and are methyl, ethyl, propyl, butyl or allyl, or they are different and are ethyl and allyl.

The compounds of the groups mentioned under B) are illustrated as follows:

Perchlorate compounds:

Examples are those of formula M(CIO ₄ ) _n , wherein M is Li, Na, K, Mg, Ca, Sr, Zn, Al, La or Ce. According to the value of M, the index n is 1 , 2 or 3. The perchlorate salts may be complexed with alcohols (polyols, cyclodextrins) or ether alcohols or ester alcohols. The ester alcohols include also the polyol partial esters. Also suitable in the case of polyhydric alcohols or polyols are their dimers, trimers, oligomers and polymers, such as di-, tri-, tetra- and poly-glycols, and di-, tri- and tetra-pentaerythritol or polyvinyl alcohol in various degrees of polymerisation. The perchlorate salts can be introduced in various known forms, for example in the form of a salt or an aqueous solution applied to a substrate, such as PVC, calcium silicate, zeolites or hyd rota I cites, or bound in a hydrotalcite by chemical reaction. Glycerol monoethers and glycerol monothioethers are preferred as polyol partial ethers. Other forms are described in EP 394 547, EP 457 471 and WO 94/24200. The perchlorates can be used in an amount of, for example, from 0.001 to 5, advantageously from 0.01 to 3, especially from 0.01 to 2, parts by weight, based on 100 parts by weight PVC.

Glycidyl compounds:

These contain the glycidyl group

O

^■ — αr—fc-Hώ, — L-A .

Si R; Ri

which is bonded directly to carbon, oxygen, nitrogen or sulfur atoms and wherein either Ri and R ₃ are both hydrogen, R ₂ is hydrogen or methyl and n=0, or R ₁ and R ₃ together are --CH ₂ -CH ₂ — or -CH ₂ -CH ₂ -CH ₂ — , in which case R ₂ is hydrogen and n=0 or 1.

I) Glycidyl and b-methylglycidyl esters obtainable by reacting a compound having at least one carboxy group in the molecule with epichlorohydrin or glycerol dichlorohydrin or b-methyl-epichlorohydrin. The reaction is advantageously carried out in the presence of bases. Aliphatic carboxylic acids may be used as compounds having at least one carboxy group in the molecule. Examples of those carboxylic acids are glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid or dimerised or trimerised linoleic acid, acrylic acid and methacrylic acid, caproic acid, caprylic acid, lauric acid, myristic acid, palmitic acid, stearic acid and pelargonic acid, and the acids mentioned in connection with the organic zinc compounds. It is, however, also possible to use cycloaliphatic carboxylic acids, such as cyclohexanecarboxylic acid, tetrahydrophthalic acid, 4-methyltetrahydrophthalic acid, hexahydrophthalic acid or 4-methylhexahydrophthalic acid. It is also possible to use aromatic carboxylic acids, such as benzoic acid, phthalic acid, isophthalic acid, trimellitic acid or pyromellitic acid. Carboxy-terminated adducts, for example of trimellitic acid and polyols, such as glycerol or 2,2-bis(4-hydroxycyclohexyl)propane can also be used. Other epoxide compounds that can be used within the scope of this invention are to be found in EP 0 506 617.

II) Glycidyl or (b-methylglycidyl) ethers obtainable by reacting a compound having at least one free alcoholic hydroxy group and/or phenolic hydroxy group and a suitably substituted epichlorohydrin under alkaline conditions, or in the presence of an acid catalyst with subsequent treatment with an alkali. Ethers of that type are derived, for example, from acyclic alcohols, such as ethylene glycol, diethylene glycol and higher poly(oxyethylene) glycols, propane-1 ,2-diol, or poly(oxypropylene) glycols, propane- 1 ,3-diol, butane-1 ,4-diol, poly(oxytetramethylene) glycols, pentane-1 ,5-diol, hexane- 1 ,6-diol, hexane-2,4,6-triol, glycerol, 1 ,1,1-trimethylolpropane, bistrimethylolpropane, pentaerythritol, sorbitol, and from polyepichlorohydrins, butanol, amyl alcohol,

pentanol, and from monofunctional alcohols, such as isooctanol, 2ethylhexanol, isodecanol and C ₇ -C ₉ alkanol and C ₉ -Cn alkanol mixtures. They are, however, also derived, for example, from cycloaliphatic alcohols, such as 1,3- or 1,4- dihydroxycyclohexane, bis(4-hydroxycyclohexyl)methane, 2,2-bis(4- hydroxycyclohexyl)propane or 1 ,1-bis(hydroxymethyl)cyclohex-3-ene, or they have aromatic nuclei, such as N,N-bis(2-hydroxyethyl)aniline or p,p'-bis(2- hydroxyethylamino)diphenylmethane. The epoxide compounds can also be derived from mononuclear phenols, such as phenol, resorcinol or hydroquinone, or they are based on polynuclear phenols, such as bis(4-hydroxyphenyl)methane, 2,2-bis(4- hydroxyphenyl)propane, 2,2-bis(3,5-di bromo-4-hydroxyphenyl)propane, 4,4'- dihydroxydiphenylsulfone, or on condensation products of phenols with formaldehyde obtained under acid conditions, such as phenol novolaks. Other possible terminal epoxides are, for example: gIycidyl-1 -naphthyl ether, glycidyl-2-phenylphenyl ether, 2-biphenylglycidyl ether, N-(2,3-epoxypropyl) phthalimide and 2,3-epoxypropyl-4- methoxyphenyl ether.

III) (N-Glycidyl) compounds obtainable by dehydrochlorinating the reaction products of epichlorohydrin with amines containing at least one aminohydrogen atom. Those amines are, for example, aniline, N-methylaniline, toluidine, n-butylamine, bis(4- aminophenyl)methane, m-xylylenediamine or bis(4-methylaminophenyl)methane, but also N,N,O-triglycidyl-m-aminophenol or N,N,O-triglycidyl-p-aminophenol. The (N- glycidyl) compounds also include, however, N,N'-di-, N,N',N"-triand N,N',N",N'"-tetra- glycidyl derivatives of cycloalkyleneureas, such as ethyleneurea or 1 ,3- propyleneurea, and N,N'-diglycidyl derivatives of hydantoins, such as 5,5- dimethylhydantoin or glycoluril and triglycidyl isocyanurate.

IV) S-Glycidyl compounds, such as di-S-glycidyl derivatives, that are derived from dithiols, such as ethane-1 ,2-dithiol or bis(4-mercaptomethylphenyl) ether.

V) Epoxide compounds containing a radical of formula I wherein Ri and R ₃ together are --CH ₂ -CH ₂ -- and n is 0 are bis(2,3-epoxycyclopentyl) ether, 2,3- epoxycyclopentylglycidyl ether or 1 ,2-bis(2,3-epoxycyclopentyloxy)ethane. An epoxy resin containing a radical of formula I wherein R ₁ and R ₃ together are -CH ₂ -CH ₂ — and n is 1 is, for example, 3,4-epoxy-6-methylcyclohexanecarboxylic acid (3',4'- epoxy-6'-methylcyclohexyl)-methyl ester. Suitable terminal epoxides are, for example (TMdenotes®):

• a) liquid digiycidyl ethers of bisphenol A, such as Araldite.TM.GY 240, Araldite.TM.AGY 250, Araldite.TM.GY 260, Araldite.TM.GY 266, Araldite.TM.GY 2600, Araldite.TM.MY 790;

• b) solid diglycidyl ethers of bisphenol A, such as Araldite.TM.GT 6071 , Araldite.TM.GT 7071 , Araldite.TM.GT 7072, Araldite.TM.GT 6063, Araldite.TM.GT 7203, Araldite.TM.GT 6064, Araldite.TM.GT 7304, Araldite.TM.GT 7004, Araldite.TM.GT 6084, Araldite.TM.GT 1999, Araldite.TM.GT 7077, Araldite.TM.GT 6097, Araldite.TM.GT 7097, Araldite.TM.GT 7008, Araldite.TM.GT 6099, Araldite.TM.GT 6608, Araldite.TM.GT 6609, Araldite.TM.GT 6610;

• c) liquid diglycidyl ethers of bisphenol F, such as Araldite.TM.GY 281 , Araldite.TM.PY 302, Araldite.TM.PY 306;

• d) solid polyglycidyl ethers of tetraphenylethane, such as CG Epoxy Resin.TM.0163;

• e) solid and liquid polyglycidyl ethers of phenolformaldehyde novolak, such as EPN 1138, EPN 1139, GY 1180, PY 307;

• f) solid and liquid polyglycidyl ethers of o-cresolformaldehyde novolak, such as ECN 1235, ECN 1273, ECN 1280, ECN 1299;

• g) liquid glycidyl ethers of alcohols, such as Shell.TM.glycidyl ether 162, Araldite.TM.DY 0390, Araldite.TM.DY 0391 ;

• h) liquid glycidyl ethers of carboxylic acids, such as Shell.TM. Cardura E terephthalic acid ester, trimellitic acid ester, Araldite.TM.PY 284;

• i) solid heterocyclic epoxy resins (triglycidyl isocyanurate), such as Araldite.TM.PT 810;

• j) liquid cycloaliphatic epoxy resins, such as Araldite.TM.CY 179;

• k) liquid N,N,O-triglycidyl ethers of p-aminophenol, such as Araldite.TM.MY 0510;

• I) tetraglycidyl-4,4'-methylenebenzamine or N,N,N',N'-tetraglycidyl- diaminophenylmethane, such as Araldite.TM.MY 720, Araldite.TM.MY 721.

Preference is given to the use of epoxide compounds having two functional groups. It is, however, also possible in principle to use epoxide compounds having one, three or more functional groups. There are predominantly used epoxide compounds, especially diglycidyl compounds, having aromatic groups. Where appropriate, a mixture of different epoxide compounds can also be used. Especially preferred as terminal epoxide compounds are diglycidyl ethers based on bisphenols, such as 2,2-bis(4-hydroxyphenyl)propane (bisphenol A), bis(4- hydroxyphenyl)-methane or mixtures of bis(ortho/para-hydroxyphenyl)methane (bisphenol F). The terminal epoxide compounds can be used in an amount of,

preferably, at least 0.1 part, for example from 0.1 to 5, advantageously from 1 to 5 based on 100 parts by weight PVC.

Beta-diketones, beta-keto esters.

1.3-Dicarbonyl compounds that can be used may be linear or cyclic dicarbonyl compounds. Preference is given to the use of dicarbonyl compounds of the following formula:

P ₁ CO CHR ₂ '-COR's wherein

• R^ is Ci -C ₂₂ alkyl, C ₅ -Ci ₀ hydroxyalkyl, C ₂ -C ₁₈ alkenyl, phenyl, phenyl substituted by OH, C ₁ -C ₄ alkyl, C ₁ -C ₄ alkoxy or by halogen, C ₇ -C ₁₀ phenylalkyl, C ₅ -C ₁₂ cycloalkyl, C ₅ -Ci ₂ cycloalkyl substituted by C-i -C ₄ alkyl, or is a group -R' ₅ -S-R' ₆ or -R' ₅ -O-R'β,

• R'2 is hydrogen, C ₁ -C ₈ alkyl, C ₂ -C ₁₂ alkenyl, phenyl, C ₇ -C ₁₂ alkylphenyl, C ₇ -C ₁₀ phenylalkyl or a group -CO-R'4,

• R' ₃ has one of the meanings given for R'i or is C ₁ -C ₁₈ alkoxy,

• R ₄ is C ₁ -C ₄ alkyl or phenyl,

• R's is Ci -Cio alkylene and

• R'e is C ₁ -C ₁₂ alkyl, phenyl, C ₇ -C ₁₈ alkylphenyl or C ₇ -C ₁₀ phenylalkyl.

Those compounds include the hydroxy group-containing diketones of EP 346 279 and the oxa- and thia-diketones of EP 307 358, as well as the keto esters based on isocyanic acid of U.S. Pat No. 4,339,383.

R' _I and R' ₃ as alkyl may be, especially, C ₁ -C ₁₈ alkyl, such as methyl, ethyl, n- propyl, isopropyl, n-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, decyl, dodecyl or octadecyl.

R^ and R' ₃ as hydroxyalkyl are, especially, a group ~(CH _2)n -OH, wherein n is 5, 6 or 7.

R'i and R' ₃ as alkenyl may be, for example, vinyl, allyl, methallyl, 1-butenyl, Ihexenyl or oleyl, preferably allyl.

R'-i and R' ₃ as phenyl substituted by OH, alkyl, alkoxy or halogen may be, for example, tolyl, xylyl, tert-butylphenyl, methoxyphenyl, ethoxyphenyl, hydroxyphenyl, chlorophenyl or dichlorophenyl.

R ¹ _! and R' ₃ as phenylalkyl are especially benzyl. R' ₂ and R' ₃ as cycloalkyl or alkylcycloalkyl are especially cyclohexyl or methylcyclohexyl.

R' ₂ as alkyl may be, especially, C ₁ -C ₄ alkyl. R' ₂ as C ₂ -C ₁₂ alkenyl may be, especially, allyl. R' ₂ as alkylphenyl may be, especially, tolyl. R' ₂ as phenylalkyl may be, especially, benzyl. R' ₂ is preferably hydrogen. R' ₃ as alkoxy may be, for example, methoxy, ethoxy, butoxy, hexyloxy, octyloxy, dodecyloxy, tridecyloxy, tetradecyloxy or octadecyloxy. R' ₅ as C ₁ -C ₁₀ alkylene is especially C ₂ -C ₄ alkylene. R' ₆ as alkyl is especially C ₄ -C ₁₂ alkyl, such as butyl, hexyl, octyl, decyl or dodecyl. R' ₆ as alkylphenyl is especially tolyl. R' ₆ as phenylalkyl is especially benzyl.

Examples of 1 ,3-dicarbonyl compounds of the above formula and their alkali metal, alkaline earth metal and zinc chelates are acetylacetone, butanoylacetone, heptanoylacetone, stearoylacetone, palmitoylacetone, lauroylacetone, 7-tert- nonylthio-heptane-2,4-dione, benzoylacetone, dibenzoylmethane, lauroylbenzoylmethane, palmitoyl-benzoylmethane, stearoyl-benzoylmethane, isooctylbenzoylmethane, 5-hydroxycapronyl-benzoylmethane, tribenzoylmethane, bis(4-methylbenzoyl)methane, benzoyl-p-chlorobenzoylmethane, bis(2- hydroxybenzoyl)methane, 4-methoxybenzoyl-benzoylmethane, bis(4- methoxybenzoyl)methane, 1 -benzoyl-1 -acetylnonane, benzoyl-acetylphenylmethane, stearoyl-4-methoxybenzoylmethane, bis(4-tert-butylbenzoyl)methane, benzoyl- formylmethane, benzoyl-phenylacetylmethane, biscyclohexanoyl-methane, di- pivaloyl-methane, 2-acetylcyclopentanone, 2-benzoylcyclopentanone, diacetoacetic acid methyl, ethyl and allyl ester, benzoyl-, propionyl- and butyryl-acetoacetic acid methyl and ethyl ester, triacetylmethane, acetoacetic acid methyl, ethyl, hexyl, octyl, dodecyl or octadecyl ester, benzoylacetic acid methyl, ethyl, butyl, 2-ethylhexyl, dodecyl or octadecyl ester, and propionyl- and butyryl-acetic acid C ₁ -C ₁₈ alkyl ester. Stearoylacetic acid ethyl, propyl, butyl, hexyl or octyl ester and polynuclear β-keto esters as described in EP 433 230 and dehydroacetic acid and the zinc, magnesium or alkali metal salts thereof.

Preference is given to 1 ,3-diketo compounds of the above formula wherein R^ is C- _I -C ₁₈ alkyl, phenyl, phenyl substituted by OH, methyl or by methoxy, C ₇ -C ₁₀ phenylalkyl or cyclohexyl, R' ₂ is hydrogen and R' ₃ has one of the meanings given for

RV

The 1 ,3-diketo compounds can be used in an amount of, for example, from 0.01 to 10, advantageously from 0.01 to 3, and especially from 0.01 to 2, parts by weight, based on 100 parts by weight PVC.

Dihydropyridines, polydihydropyridines.

Suitable monomeric, dihydropyridines are described, for example, in FR 20 39

496, EP 2007, EP 0 362 012, EP 0 286 887 and EP 0 024 754. Preference is given to those of the formula

IhC NM CHi

wherein Z is CO ₂ CH ₃ , CO ₂ C ₂ H ₅ , CO ₂ " Ci ₂ H ₂₅ or CO ₂ C ₂ H ₄ S" C ₁₂ H ₂₅ .

Suitable polydihydropyridines are especially compounds of the following formula

wherein T is Ci -C ₂₂ alkyl that is unsubstituted or substituted by Ci -C ₁₈ alkoxy, C-i - da alkylthio, hydroxy, acryloyloxy, methacryloyloxy, halogen, phenyl or by naphthyl;

• C ₅ -Cio aryl that is unsubstituted or substituted by C ₁ -C ₁₈ alkyl, C ₁ -C ₁₈ alkoxy or by halogen and that may also be heterocyclic;

. C ₃ -C ₁₀ alkenyl, CH ₃ -CO-CH ₂ -CO-OR ¹ -, CH ₃ -CO-CH ₂ -COO-R ¹ , CH ₃ - -C(NR ¹ VCH-COOR- or CH ₃ -C(NR ¹ VCHCO-OR ¹ -;

• L has the same meanings as T or is a tri- or poly-valent radical from an unsubstituted or C-i -C ₁₂ alkoxy-, C ₁ -C _t2 thioalkoxy-, C ₆ -Ci ₀ aryl-, C ₁ -C ₁₂ carboxy- or hydroxy-substituted straight-chained or branched alkyl group,

• m and n are numbers from O to 20,

• k is O oM ,

• j is a number from 1 to 6 and the conditions j (k+m+n)>1 and m+n>0 are satisfied,

• R and R' are each independently of the other methylene or phenylene or an alkylene group of the type --(-- C _p H _2p — X-) _t C _p H _2p - that is unsubstituted or carries substituents from the series C ₁ -Ci ₂ alkoxy, C-i -C ₁₂ thioalkoxy, C ₆ -Ci ₀ aryl, C ₁ -C ₁₂ carboxy and hydroxy, o p is from 2 to 18, o t is from O to 10,

o X is oxygen or sulfur, o or, when k is 0 and j>1 , R and R' together with L form a direct bond,

• R" is hydrogen, or C ₁ -Ci ₈ alkyl, C ₂ -Ci ₈ alkoxycarbonyl or C ₆ -Ci ₀ aryl each of which is unsubstituted or substituted by one or more C ₁ -C ₁₂ alkyl, C ₁ -C ₈ alkoxy, halogen or NO ₂ substituents,

• and the two R" ¹ radicals are identical or different and are hydrogen, C ₁ -C ₁₈ alkyl, Ci -C ₁₈ -hydroxyalkyl or C ₁ -C ₁₈ alkoxyalkyl or together are uninterrupted or O-interrupted C ₃ -C ₅ alkylene,

• or are straight-chained or branched C ₂ -C ₂₂ alkenyl.

Such compounds are described in more detail in EP 0 286 887.

ThiodiethyIene-bis[5-methoxycarbonyl-2,6-di methyl-1 ,4-dihydropyridine-3- carboxylate] is especially preferred.

The (Poly-)Dihydropyridine can be present in chlorine containing polymer in an amount of from 0,001 to 5 parts and especially 0,005 to 1 parts by weight based on 100 parts by weight PVC.

Polyols.disaccharide alcohols

Examples of suitable compounds of that type are: pentaerythritol, dipentaerythritol, tripentaerythritol, bistrimethylolpropane, bistrimethylolethane, trismethylolpropane, inosite, polyvinylalcohol, sorbitol, maltite, isomaltite, lactite, lycasin, mannitol, lactose, leucrose, tris(hydroxyethyl) isocyanurate, palatinite, tetramethylolcyclohexanol, tetramethylolcyclopentanol, tetramethylolcyclopyranol, glycerol, diglycerol, polyglycerol, thiodiglycerol or 1-0-a-D- glycopyranosyl-D-mannitol dihydrate. Of those compounds, preference is given to the disaccharide alcohols.

The polyols can be used in an amount of, for example, from 0.01 to 5, advantageously from 0.1 to 5, parts by weight, based on 100 parts by weight PVC.

Sterically hindered amines (tetraalkylpiperidine compounds) The sterically hindered amines, especially piperidine compounds that can be used according to the invention are known especially as light stabilisers. Those compounds contain one or more groups of the formula

IJ ₃ C- . N^^.Ctlj ^lhC [ J ^CH>

/\

They may be compounds of relatively low molecular weight (<700) or of relatively high molecular weight. In the latter case they may be oligomeric or polymeric products. Preference is given to tetramethylpiperidine compounds having a molecular weight of more than 700 that contain no ester groups.

Especially important as stabilisers are the following classes of tetramethylpiperidine compounds.

In the following classes a) to f), substituents having subscript indices in their formula drawings correspond (for technical reasons) to the substituents having superscript indices in the description or definition belonging to the formula drawing in question. Thus, for example, the substituent "R-i " in formula (II) corresponds to "R ¹ " in the descriptions. a) Compounds of formula Il

(ID

FIjC CSl ₃

λγ-N V-O- -SU

HjC πij

wherein n is a number from 1 to 4, preferably 1 or 2,

• R ¹ is hydrogen, oxy, Ci -C ₁₂ alkyl, C ₃ -C ₈ alkenyl, C ₃ -C ₈ alkynyl, C ₇ -Ci ₂ aralkyl, C ₁ -C ₈ alkanoyl, C ₃ -C ₅ alkenoyl, glycidyl or a group --CH ₂ CH(OH)-Z, wherein Z is hydrogen, methyl or phenyl, R ¹ being preferably C ₁ -C ₄ alkyl, allyl, benzyl, acetyl or acryloyl, and,

• when n is1 , R ² is hydrogen, C-, -C ₁₈ alkyl that is uninterrupted or interrupted by one or more oxygen atoms, cyanoethyl, benzyl, glycidyl, a monovalent radical of an aliphatic, cycloaliphatic, araliphatic, unsaturated or aromatic carboxylic acid, carbamic acid or phosphorus-containing acid or a monovalent silyl radical, preferably a radical of an aliphatic carboxylic acid having from 2 to 18 carbon atoms, a cycloaliphatic carboxylic acid having from 7 to 15

carbon atoms, an α.β-unsaturated carboxylic acid having from 3 to 5 carbon atoms or an aromatic carboxylic acid having from 7 to 15 carbon atoms, and, when n is 2, R ² is C ₁ -C ₁₂ -alkylene, C ₄ -C ₁₂ alkenylene, xylylene, a divalent radical of an aliphatic, cycloaliphatic, araliphatic or aromatic dicarboxylic acid, dicarbamic acid or phosphorus-containing acid or a divalent silyl radical, preferably a radical of an aliphatic dicarboxylic acid having from 2 to 36 carbon atoms, a cycloaliphatic or aromatic dicarboxylic acid having from 8 to 14 carbon atoms or an aliphatic, cycloaliphatic or aromatic dicarbamic acid having from 8 to 14 carbon atoms, and, when n is 3, R ² is a trivalent radical of an aliphatic, cycloaliphatic or aromatic tricarboxylic acid, an aromatic tricarbamic acid or a phosphorus-containing acid or a trivalent silyl radical and, when n is 4, R ² is a tetravalent radical of an aliphatic, cycloaliphatic or aromatic tetracarboxylic acid.

When any of the substituents are C ₁ -C ₁₂ alkyl, they are, for example, methyl, ethyl, n-propyl, n-butyl, sec-butyl, tert-butyl, n-hexyl, n-octyl, 2-ethyI-hexyl, n-nonyl, n- decyl, n-undecyl or n-dodecyl.

In the meaning of C ₁ -Ci ₈ alkyl, R ² may be, for example, the groups listed above and, in addition, for example, n-tridecyl, n-tetradecyl, n-hexadecyl or n-octadecyl.

When R ¹ is C ₃ -C ₈ alkenyl, it may be, for example, 1-propenyl, allyl, methallyl, 2- butenyl, 2-pentenyl, 2-hexenyl, 2-octenyl or 4-tert-butyl-2-butenyl.

R ¹ as C ₃ -C ₈ alkynyl is preferably propargyl.

As C ₇ -C ₁₂ aralkyl, R ¹ is especially phenethyl and more especially benzyl.

R ¹ as C- _I -C ₈ alkanoyl is, for example, formyl, propionyl, butyryl, octanoyl, but preferably acetyl, and as C ₃ -C ₅ alkenoyl is especially acryloyl.

When R ² is a monovalent radical of a carboxylic acid, it is, for example, an acetic acid, caproic acid, stearic acid, acrylic acid, methacrylic acid, benzoic acid or β-(3,5- di-tert-butyl-4-hydroxyphenyl)-propionic acid radical.

When R ² is a divalent radical of a dicarboxylic acid, it is, for example, a malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid, sebacic acid, maleic acid, phthalic acid, dibutylmalonic acid, dibenzylmalonic acid, butyl-(3,5di-tert-butyl-4- hydroxybenzyl)-malonic acid or bicycloheptenedicarboxylic acid radical.

When R ² is a trivalent radical of a tricarboxylic acid, it is, for example, a trimellitic acid or nitrilotriacetic acid radical.

When R ² is a tetravalent radical of a tetracarboxylic acid, it is, for example, the tetravalent radical of butane-1 ,2,3,4-tetracarboxylic acid or of pyromellitic acid.

When R ² is a divalent radical of a dicarbamic acid, it is, for example, a hexamethylenedicarbamic acid or a 2,4-toluylene-dicarbamic acid radical.

The following compounds are examples of polyalkylpiperidine compounds of that class:

• 1 ) 4-hydroxy-2,2,6,6-tetramethylpiperidine

• 2) 1-allyl-4-hydroxy-2,2,6,6-tetramethylpiperidine

• 3) 1-benzyl-4-hydroxy-2,2,6,6-tetramethylpiperidine

• 4) 1 -(4-tert-butyl-2-butenyl)-4-hydroxy-2,2,6,6-tetramethylpiper idine

• 5) 4-stearoyloxy-2,2,6,6-tetramethylpiperidine

• 6) 1-ethyl-4-salicyloyloxy-2,2,6,6-tetramethylpiperidine

• 7) 4-methacryloyloxy-1 ,2,2,6,6-pentamethylpiperidine

• 8) 1 ,2,2,6,6-pentamethylpiperidin-4-yl-β-(3,5-di-tert-butyl-4-h ydroxyphenyl) propionate

• 9) di(1-benzyl-2,2,6,6-tetramethylpiperidin-4-yl) maleinate

• 10) di(2,2,6,6-tetramethy!piperidin-4-yl) succinate

• 11) di(2,2,6,6-tetramethylpiperidin-4-yl) glutarate

• 12) di(2,2,6,6-tetramethylpiperidin-4-yl) adipate

• 13) di(2,2,6,6-tetramethylpiperidin-4-yl) sebacate

• 14) di(1 ,2,2,6,6-pentamethylpiperidin-4-yl) sebacate

• 15) di(1 ,2,3,6-tetramethyl-2,6-diethylpiperidin-4-yl) sebacate

• 16) di(1-allyl-2,2,6,6-tetramethylpiperidin-4-yl) phthalate

• 17) 1-propargyl-4β-cyanoethyloxy-2,2,6,6-tetramethylpiperidine

• 18) 1-acetyl~2,2,6,6-tetramethylpiperidin-4-yl acetate

• 19) trimellitic acid tri(2,2,6,6-tetramethylpiperidin-4-yl) ester

• 20) 1-acryloyl-4-benzyloxy-2,2,6,6-tetramethylpiperidine

• 21) diethylmalonic acid di(2,2,6,6-tetramethylpiperidin-4-yl) ester

• 22) dibutylmalonic acid di(1 ,2,2,6,6-pentamethylpiperidin-4-yl) ester

• 23) butyl-(3,5-di-tert-butyl-4-hydroxybenzyl)-malonic acid di(1 ,2,2,6,6pentamethylpiperidin-4-yl) ester

• 24) dibenzyl-malonic acid di(1 ,2,2,6,6-pentamethylpiperidin-4-yl) ester

• 25) dibenzyl-malonic acid di(1 ^Aβ-tetramethyl^θ-diethyl-piperidin^-yl) ester

• 26) hexane-1 \6'-bis(4-carbamoyloxy-1 -n-butyl-2,2,6,6-tetramethyl-piperidine)

• 27) toluene-2',4'-bis(4-carbamoyloxy-1-n-propyl-2,2,6,6-tetramet hylpiperidine)

• 28) dimethyl-bis(2,2,6,6-tetramethylpiperidin-4-oxy)silane

• 29) phenyl-tris(2,2,6,6-tetramethylpiperidin-4-oxy)silane

« 30) tris(1-propyl-2,2,6,6-tetramethylpiperidin-4-yl)phosphite β 31) tris(1-propyl-2,2,6,6-tetramethylpipericlin-4-yl) phosphate

• 32) phenyl-[bis(1 ,2,2,6,6-pentamethylpiperidin-4-yl)]phosphonate

• 33) 4-hydroxy-1, 2,2,6, 6-pentamethylpiperidine

• 34) 4-hydroxy-N-hydroxyethyl-2,2,6,6-tetramethylpiperidine

• 35) 4-hydroxy-N-(2-hydroxypropyl)-2,2,6,6-tetramethylpiperidine

• 36) 1-glycidyl-4-hydroxy-2,2,6,6-tetramethylpiperidine

b) Compounds of formula (III)

ait) rjjc ciii

rijc CU ₁

wherein n is the number 1 or 2,

« R ¹ is as defined for a),

• R ³ is hydrogen, C ₁ -C ₁₂ alkyl, C ₂ -C ₅ hydroxyalkyl, C ₅ -C ₇ cycloalkyl, C ₇ -C ₈ aralkyl, C ₂ -C ₁₈ alkanoyl, C ₃ -C ₅ alkenoyl or benzoyl, and,

• when n is 1 , R ⁴ is hydrogen, C ₁ -C ₁₈ alkyl, C ₃ -C ₈ alkenyl, C ₅ -C ₇ cycloalkyl, C ₁ -C ₄ alkyl substituted by a hydroxy, cyano, alkoxycarbonyl or carbamide group, glycidyl, a group of the formula -CH ₂ -CH(OH)-Z or of the formula -CONH- Z, wherein Z is hydrogen, methyl or phenyl; and, when n is 2, R ⁴ is C ₂ -C ₁₂ alkylene, C ₆ -C ₁₂ arylene, xylylene, a -CH ₂ -CH(OH)-CH ₂ — group or a group -CH ₂ -CH(OH)-CH ₂ -0-D-O-, wherein D is C ₂ -C ₁₀ alkylene, C ₆ -C ₁₅ arylene or C ₆ -Ci ₂ cycloalkylene, or, o with the proviso that R ³ is not alkanoyl, alkenoyl or benzoyl,

• R ⁴ may also be a divalent radical of an aliphatic, cycloaliphatic or aromatic dicarboxylic acid or dicarbamic acid or also the group -CO— or,

• when n is 1 , R ³ and R ⁴ together may be the divalent radical of an aliphatic, cycloaliphatic or aromatic 1 ,2- or 1 ,3-dicarboxylic acid.

When any of the substituents are C-i -C ₁₂ - or C ₁ -Ci ₈ -alkyl, they are as already defined above under a). When any of the substituents are C ₅ -C ₇ cycloalkyl, they are especially cyclohexyl.

As C ₇ -C ₈ aralkyl, R ³ is especially phenylethyl or more especially benzyl. As C ₂ -C ₅ hydroxyalkyl, R ³ is especially 2-hydroxyethyl or 2-hydroxy propyl.

R ³ as C ₂ -C ₁₈ alkanoyl is, for example, propionyl, butyryl, octanoyl, dodecanoyl, hexadecanoyl, octadecanoyl, but preferably acetyl, and as C ₃ -C ₅ alkenoyl is especially acryloyl.

When R ⁴ is C ₂ -C ₈ alkenyl, then it is, for example, allyl, methallyl, 2-butenyl, 2- pentenyl, 2-hexenyl or 2-octenyl.

R ⁴ as C ₁ -C ₄ alkyl substituted by a hydroxy, cyano, alkoxycarbonyl or carbamide group may be, for example, 2-hydroxyethyl, 2-hydroxypropyl, 2-cyanoethyl, methoxycarbonyl methyl, 2-ethoxycarbonylethyl, 2-aminocarbonylpropyl or 2- (dimethylaminocarbonyl)-ethyl.

When any of the substituents are C ₂ -C ₁₂ alkylene, they are, for example, ethylene, propylene, 2,2-dimethylpropylene, tetramethylene, hexamethylene, octamethylene, decamethylene or dodecamethylene.

When any of the substituents are C ₆ -Ci ₅ arylene, they are, for example, o-, m- or p-phenylene, 1 ,4-naphthylene or 4,4'-diphenylene.

As C ₆ -Ci ₂ cycloalkylene, D is especially cyclohexylene.

The following compounds are examples of polyalkylpiperidine compounds of that class:

• 37) N,N'-bis(2,2,6,6-tetramethylpiperidin-4-yl)hexamethylene-1 ,6-diamine

• 38) N,N'-bis(2,2,6,6-tetramethylpiperidin-4-yl)hexamethylene-1 ,6-diacetamide and 1 ,6-diformamide

• 39) 1 -acetyl-4-(N-cyclohexylacetamido)-2,2,6,6-tetramethylpiperid ine

• 40) 4-benzoylamino-2,2,6,6-tetramethylpiperidine

• 41 ) N,N'-bis(2,2,6,6-tetramethylpiperidin-4-yl)-N,N'-dibutyl-adi pamide

• 42) N,N'-bis(2,2,6,6-tetramethylpiperidin-4-yl)-N,N ¹ -dicyclohexyl-2- hydroxypropylene-1 ,3-diamine

• 43) N,N'-bis(2,2,6,6-tetramethylpiperidin-4-yl)-p-xylylene-diami ne β 44) N,N'-bis(2,2,6,6-tetramethylpiperidin-4-yl)succine-diamide

• 45) N-(2,2,6,6-tetramethylpiperidin-4-yl)-β-aminodipropionic acid di(2, 2,6,6- tetramethylpiperidin-4-yl) ester

• 46) the compound of the formula

m II,) λ en",3

_v , M ) N — CHj- CU(OH!- ~ CUj-O

CfI /,V CHj

^JJ- _™ ^ _™ -^£ _j

CIt, /."Hj, r

CUT- N N-CH ₃ -CH(OHi — CHj-O

/<^— ' C ₁ JI ₀

CCIJ CHJ

• 47) 4-(bis-2-hydroxyethyl-amino)-1 ,2,2,6,6-pentamethylpipericline 48) 4- (3-methyl-4-hydroxy-5-tert-butyl-benzoic acid amido)-2,2,6,6- tetramethylpiperidine

49) 4-methacrylamido-1 ,2,2,6,6-pentamethylpiperidine

c) Compounds of formula (IV)

(IVJ

HjC CHJ

RT~ N

H ₅ C C ⁽ Ij

wherein n is the number 1 or 2,

• R ¹ is as defined under a) and,

• when n is 1 , R ⁵ is C ₂ -C ₈ alkylene or C ₂ -C ₈ hydroxyalkylene or C ₄ -C ₂₂ acyloxyalkylene, and, when n is 2, R ⁵ is the group (~CH ₂₎₂ C(CH ₂ -) ₂ .

When R ⁵ is C ₂ -C ₈ alkylene or C ₂ -C ₈ hydroxyalkylene, it is, for example, ethylene, 1-methyl-ethylene, propylene, 2-ethyl-propylene or 2-ethyl-2- hydroxymethylpropylene.

As C ₄ -C ₂₂ acyloxyalkylene, R ⁵ is, for example, 2-ethyl-2-acetoxymethylpropylene.

The following compounds are examples of polyalkylpiperidine compounds of that class:

• 50) 9-aza-8,8,10,10-tetraπnethyl-1,5-dioxaspiro[5.5]undecane

• 51 ) 9-aza-8,8,10,10-tetramethyl-3-ethyl-1 ,5-dioxaspiro[5.5]undecane

• 52) 8-aza-2,7,7,8,9,9-hexamethyl-1 ,4-dioxaspiro[4.5]decane

« 53) 9-aza-3-hydroxymethyl-3-ethyl-8,8,9,10,10-pentamethyl-1 ,5- dioxaspiro[5.5]undecane

• 54) 9-aza-3-ethyl-3-acetoxymethyl-9-acetyl-8,8,10,10-tetramethyl - 1 ,5dioxaspiro[5.5]undecane

• 55) 2,2,6,6-tetramethylpiperidine-4-spiro-2 ^l -(r,3'-dioxane)-5'-spiro-5"-(1",3" dioxane)-2"-spiro-4 ^I "-(2" ^l ,2 ¹ ",6 ^I ",6" ^I -tetramethylpipeπdine).

d) Compounds of formulae VA, VB and VC

(Vλ)

K?

(VIl)

(VO

wherein n is the number 1 or 2,

• R ¹ is as defined under a),

• R ⁶ is hydrogen, C ₁ -C ₁₂ alkyl, ailyl, benzyl, glycidyl or C ₂ -C ₆ alkoxyalkyl and,

• when n is 1 , R ⁷ is hydrogen, C ₁ -C ₁₂ alkyl, C ₃ -C ₅ alkenyl, C ₇ -C ₉ aralkyl, C ₅ - C ₇ cycloalkyl, C ₂ -C ₄ hydroxyalkyl, C ₂ -C ₆ alkoxyalkyl, C ₆ -C ₁₀ aryl, glycidyl or a group of the formula ~(CH ₂ ) _P ~COO-Q or of the formula ~(CH ₂ ) _P --O~CO~ Q, wherein p is 1 or 2 and Q is C ₁ -C ₄ alkyl or phenyl, and, when n is 2, R ⁷ is C ₂ -C ₁₂ alkylene, C ₄ -Ci ₂ alkenylene, C ₆ -C ₁₂ arylene, a group --CH ₂ -- CH(OH)-CH ₂ -0-D-CH ₂ -CH(OH)-CH ₂ -, wherein D is C ₂ -C ₁₀ alkylene, C ₆ -C ₁₅ arylene, C ₆ -C ₁₂ cycloalkylene, or a group -CH ₂ CH(OZ)CH ₂ -(OCH ₂

-CH(OZ')CH ₂ ) ₂ - wherein Z' is hydrogen, C ₁ -C ₁₈ alkyl, allyl, benzyl, C ₂ -C ₁₂ alkanoyl or benzoyl, T ₁ and T ₂ are each independently of the other hydrogen, Ci -C ₁₈ alkyl, or unsubstituted or halo- or C ₁ -C ₄ alkyl-substituted C ₆ -C ₁₀ aryl or C ₇ -C ₉ aralkyl, or Ti and T ₂ together with the carbon atom that binds them form a C ₅ -Ci ₂ cycloalkane ring.

When any of the substituents are C ₁ -C ₁₂ alkyl, they are, for example, methyl, ethyl, n-propyl, n-butyl, sec-butyl, tert-butyl, n-hexyl, n-octyl, 2-ethyl-hexyl, n-nonyl, n- decyl, n-undecyl or n-dodecyl.

Any substituents having the definition of C ₁ -C ₁₈ alkyl may be, for example, the groups listed above and in addition, for example, n-tridecyl, n-tetradecyl, n-hexadecyl or n-octadecyl.

When any of the substituents are C ₂ -C ₆ alkoxyalkyl, they are, for example, methoxymethyl, ethoxymethyl, propoxymethyl, tert-butoxymethyl, ethoxyethyl, ethoxypropyl, n-butoxyethyl, tert-butoxyethyl, isopropoxyethyl or propoxypropyl.

When R ₇ is C ₃ -C ₅ alkenyl, it is, for example, 1-propenyl, allyl, methallyl, 2butenyl or 2-pentenyl.

As C ₇ -C ₉ aralkyl, R , T ₁ and T ₂ are especially phenethyl or more especially benzyl. When T ₁ and T ₂ together with the carbon atom form a cycloalkane ring, that ring may be, for example, a cyclopentane, cyclohexane, cyclooctane or cyclododecane ring.

When R ⁷ is C ₂ -C ₄ hydroxyalkyl, it is, for example, 2-hydroxyethyl, 2hydroxypropyl, 2-hydroxybutyl or 4-hydroxybutyl.

As C ₆ -Cio aryl, R ⁷ , T ₁ and T ₂ are especially phenyl, a- or β-naphthyl, which are unsubstituted or substituted by halogen or by C ₁ -C ₄ alkyl.

When R ⁷ is C ₂ -C ₁₂ alkylene, it is, for example, ethylene, propylene, 2,2dimethylpropylene, tetramethylene, hexamethylene, octamethylene, decamethylene or dodecamethylene.

As C ₄ -C ₁₂ alkenylene, R ⁷ is especially 2-butenylene, 2-pentenylene or 3- hexenylene.

When R ⁷ is C ₆ -Ci ₂ arylene, it is, for example, o-, m- or p-phenylene, 1 ,4naphthylene or 4,4'-diphenylene.

When Z ¹ is C ₂ -Ci ₂ alkanoyl, it is, for example, propionyl, butyryl, octanoyl, dodecanoyl, but preferably acetyl.

• D as C ₂ -Cio alkylene, C ₆ -Ci ₅ arylene or C ₆ -C ₁₂ cycloalkylene is as defined under b).

The following compounds are examples of polyalkylpiperidine compounds of that class:

• 56) 3-benzyl-1 ,3,8-triaza-7,7,9,9-tetramethylspiro[4.5]decane-2,4-dione

• 57) 3-n-octyl-1 ,3,8-triaza-7,7,9,9-tetramethylspiro[4.5]decane-2,4-dione

• 58) 3-allyl-1 ,3,8-triaza-1 ,7,7,9,9-pentamethylspiro[4.5]decane-2,4-dione

• 59) 3-glycidyl-1 ,3,8-triaza-7,7,8,9,9-pentamethylspiro[4.5]decane-2,4-dione

• 60) 1 ,3,7,7,8,9,9-heptamethyl-1 ,3,8-triazaspiro[4.5]decane-2,4-dione

• 61 ) 2-isopropyl-7,7,9,9-tetramethyl-1 -oxa-3,8-diaza-4-oxo-spiro[4.5]decane

• 62) 2,2-di butyl-7,7,9,9-tetramethyl-1-oxa-3,8-diaza-4-oxo-spiro[4.5]de cane

• 63) 2,2,4,4-tetramethyl-7-oxa-3,20-diaza-21-oxo-dispiro[5.1.11.2 Jhenicosane

• 64) 2-butyl-7,7,9,9-tetramethyl-1 -oxa-4,8-diaza-3-oxo-spiro[4.5]decane

• 65) 8-acetyl-3-dodecyl-1 ,3,8-triaza-7,7,9,9-tetramethylspiro[4.5]decane- 2,4dione or the compounds of the following formulae:

6!i) Cir> C)Jj CUJ CiI,

V ^^ NU-C=O O=C

CH _γ - N Y N — Cih

V — ' c — K — CiIiCIi(OHjCIt-- foαtj— cu(oiι>αy ₂ — N — c

CHj CH) O O C13> CH ₁

07; CtIj _y Cll.i CtI., _y CHj

NtI-C=O O=C — MI

\ .

CU ₅ - N S — UIj

C — N — (CHv;,; - N — C cut, en., _o en, αij

(>Sf CUj fU;, CH ₃ CUj.

NIl-C=O O=C — XII

IIS NU

-conl ϊmmά

69; ttiC Cη _j

c— N — cr rø I ₁ OXKr ₁ Ii ι _s

e) Compounds of formula Vl

-RK.

wherein n is the number 1 or 2 and R ⁸ is a group of the formula

rib ,cn>

-K-<λi - »|

ClI, CH.,

wherein R ¹ is as defined under a),

. E is -O- or -NR ¹¹ -,

• A is C ₂ -C ₆ alkylene or ~(CH ₂ )3 — O- and

• x is the number 0 or 1 ,

. R ⁹ is identical to R ⁸ or is one of the groups -NR ¹¹ R ¹² , -O ¹³ , -NHCH ₂ OR ¹³ or -N(CH ₂ OR ¹³⁾ ₂ ,

• when n=1 , R ¹⁰ is identical to R ⁸ or R ⁹ and, when n=2, R ¹⁰ is a group -E-B-E- -, wherein B is C ₂ -C ₆ alkylene that is uninterrupted or interrupted by -N(R ^11)~

β R ¹¹ is C ₁ -C ₁₂ alkyl, cyclohexyl, benzyl or C ₁ -C ₄ hydroxyalkyl or a group of the formula

α CU _J CH/*

N— K..

CU, CHJl

R ¹² is C ₁ -C ₁₂ alkyl, cyclohexyl, benzyl, C-i -C ₄ hydroxyalkyl and

R ¹³ is hydrogen, C ₁ -C ₁₂ alkyl or phenyl, or

R ¹¹ and R ₁₂ together are C ₄ -C ₅ alkylene or C ₄ -C ₅ oxaalkylene, for example

O Dt N -- A. rt-

-CNiCUv __y -c Irøib

are a group of the formula

'"" ^{λ ' ' '} ' _\ . I .l^C Hi ™""""v *"" ^■ *!_ I IjL. Ji -^- — — i

O or N — Ss

' ' CIl ₂ CH ₂ :'- — ' ' ClIiCM j '

or alternatively R ¹¹ and R ¹² are each a group of the formula

>

- MI — λ

I! J

) J cn ₃ Oh T -K

,CH,

I

When any of the substituents are C ₁ -Ci ₂ alkyl, they are, for example, methyl, ethyl, n-propyl, n-butyl, sec-butyl, tert-butyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, n- decyl, n-undecyl or n-dodecyl.

When any of the substituents are C ₁ -C ₄ hydroxyalkyl, they are, for example, 2- hydroxyethyl, 2-hydroxypropyl, 3-hydroxy propyl, 2-hydroxybutyl or 4hydroxybutyl.

When A is C ₂ -C ₆ alkylene, it is, for example, ethylene, propylene, 2,2- dimethylpropylene, tetramethylene or hexamethylene.

When R ¹¹ and R ¹² together are C ₄ -C ₅ alkylene or C ₄ -C ₅ oxaalkylene, they are, for example, tetramethylene, pentamethylene or 3-oxapentamethylene.

The compounds of the following formulae are examples of polyalkylpiperidine compounds of that class:

?!) I Olj

H 1I I,))CLL.. _S ,CK,

II bjCe

N N—- tCiHe

cn _j , eu, I a i _j πI.,

CIt-. — S ) >3 "^ J N ( N — CJI..

CH ₅ cit, αi, αι,

72)

K

λλ

wherein R=

Hf CMj

^■ — MU-ClIX)I ₂ CtIj — 0 ( N-CU ₃

UjC CJi,

SU

. wherein R is

whcruin R«

Wherein R-i

m

CH ₅ Cits ^'

r _s π,7— K— / MT

* ^■ at, ah

Ci ⁽ Jn — N' N Kl KCHi-

-coniinticcl I

-C ₁ H,,

111, CKj N-^N HK C(Ii

HO— CIl h. Ctl. - S > N N S ( N- -nrjCiij- ^■ 0»

Cl^ CUx Cih CU,

SO) CHj-HI=CH. N _^ .XIh

N ^* "" ^* v i U 'j

IhC CHx A CiU CIh

H»t"= JU^HJT- N ) N S* N ( N-CHj-TtI = CITj

IhC CUt CHi CHj

f) Oligomeric or polymeric compounds, the structural repeating unit of which contains one or more 2,2,6,6-tetraalkylpiperidine radicals of formula (I), especially polyesters, polyethers, polyamides, polyamines, polyurethanes, polyureas, polyaminotriazines, poly(meth)acrylates, polysiloxanes, poly(meth)acrylamides and the copolymers thereof that contain such radicals.

Examples of 2,2,6,6-polyalkylpiperidine light stabilisers of that class are the compounds of the following formulae wherein m is a number from 2 to approximately 200.

95) I"" I

O wlan«ia R = H υι CUj

<)d)

NU

(CHj) _J

HyCi(R)N- ^ ^" ">i X — (Cfl;>j— N- •a'

*«y ^N (C»i)i

NH

N(HJC ₁ Hn

1 λ» t.^

ITVC ₁ (RJN ¹ .λ' N.λ ^' . N(R)C ₁ JI ₁ ,

HZ-V I I ^ClI., wlxreir. R " HjC ^*" "NH ^CH;

:ιϊid H'= HsC ₄ (K)S 1 N X NXU)C-Ht. oi (1

{obtainable by reacting the reaction product of trichlorotriazine and NH ₂ ~(CH ₂₎ 3 -- NH--(CH ₂₎₂ -(CHa) ₃ --NH ₂ with 4-N-butyl-2,2,6 ₁ 6-tetramethylpiperidine}

Of those classes, classes e) and f) are especially suitable, especially those tetraalkylpiperidine compounds that contain s-triazine groups. Also especially suitable are compounds 74, 76, 84, 87, 92, 95 and 96.

The preparation of the N-piperidinyl-triazines is known from the literature (cf., for example, Houben-Weyl "Methoden der organischen Chemie", Vol. VIII, p. 233-237, 3 ^rd Ed., Thieme Verlag Stuttgart 1971). There may be used as starting material for the reaction with various N-piperidylamines cyanuric chloride, diamino-chloro-1 ,3,5- triazine or variously substituted bisdialkylamino-chloro-1 ,3,5-triazines or dialkylamino-

or alkylamino-dichloro-1 ,3,5-triazines.

Technically important examples of tetra- and penta-alkylpiperidine compounds are: bis(2,2,6,6-tetramethyl-piperidyl) sebacate, bis(2,2,6,6tetramethyl-piperidyl) succinate, bis(1 , 2,2,6, 6-pentamethylpiperidyl) sebacate, n-butyl-3,5-di-tert-butyl-4- hydroxybenzyl-malonic acid bis(1 ,2,2,6,6pentamethylpiperidyl) ester, the condensation product of 1-hydroxyethyl-2,2,6,6-tetramethyl-4-hydroxy-piperidine and succinic acid, the condensation product of N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl)- hexamethylenediamine and 4-tert-octylamino-2,6-dichloro-1 ,3,5-s-triazine, tris(2,2,6,6-tetramethyl-4-piperidyl)nitrilotriacetate, tetrakis(2,2,6,6-tetramethyl-4- piperidyl)-1 ,2,3,4-butanetetraoate, 1 ,1'-(1 ,2-ethanediyl)-bis(3,3,5,5-tetramethyl- piperazinone), 4-benzoyl-2,2,6,6-tetramethylpiperidine, 4-stearyloxy-2, 2,6,6- tetramethylpiperidine, bis(1 ,2,2,6,6-pentamethylpiperidyl)-2-n-butyl-2-(2-hydroxy-3,5- di-tert-butylbenzyl) malonate, 3-n-octyl-7,7,9,9-tetramethyl-1 ,3,8- triazaspiro[4.5]decane-2,4-dione, bis(1-octyloxy-2,2,6,6-tetramethylpiperidyl) sebacate, bis(1-octyloxy-2,2,6,6-tetramethylpiperidyl) succinate, the condensation product of N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl)hexamethylenediamin e and 4- morpholino-2,6-dichloro-1 ,3,5-triazine, the condensation product of 2-chloro-4,6-di(4- n-butylamino-2,2,6,6-tetramethylpiperidyl)-1 ,3,5-triazine and 1 ,2-bis(3- aminopropylamino)ethane, the condensation product of 2-chloro-4,6-di(4-n- butylamino-1 ,2,2,6,6-pentamethylpiperidyl)-1 ,3,5-triazine and 1 ,2-bis(3- aminopropylamino)ethane, 8-acetyl-3-dodecyl-7,7,9,9-tetramethyl-1 ,3,8- triazaspiro[4.5]decane-2,4-dione, 3-dodecyl-1-(2,2,6,6-tetramethyl-4- piperidyl)pyrrolidine-2,5-dione, 3-dodecyl-1-(1 ,2,2,6, 6-pentamethyl-4-piperidyl)- pyrrolidine-2,5-dione.

Instead of a single sterically hindered amine, it is possible within the scope of the present invention also to use a mixture of different sterically hindered amines.

The amount of sterically hindered amine added depends on the desired degree of stabilisation. In general, from 0.01 to 0.5% by weight, especially from 0.05 to 0.5% by weight, based on the polymer, is added.

Hydrotalcites and alkali (alkaline earth) aluminosilicates (zeolites).

The chemical composition of these compounds is known to a person skilled in the art, for example from patent specifications DE 38 43 581 , U.S. Pat. No. 40,00,100, EP 062 813, WO 93/20135.

Compounds from the hydrotalcite series can be described by general formula VII

M ² V _x M ³⁺ _x (OH) ₂ (A ^b -)x _/b *αη ₂ O (VII) wherein

• M ²⁺ =one or more of the metals from the group Mg, Ca, Sr, Zn or Sn, . M ³⁺ =AI, or B, o A ⁿ is an anion having the valency n, o b is a number from 1 to 2,

• 0<x£ 0.5,and

• m is a number from 0 to 20.

Preferably,

. A ⁿ =OH\ CIO ₄ -, HCO ₃ ^" , CH ₃ COO ^" , C ₆ H ₅ COO ^" , CO ₃ ² -, (CHOHCOO) ₂ ² -, (CH ₂ COO) ₂ ² -, CH ₃ CHOHCOO-, HPO ₃ ^" or HPO ₄ ² -

Examples of hydrotalcites are

. Al ₂ O ₃ .6MgO.CO ₂ .12H ₂ O (i), Mg ₄ ,5 Al ₂ (OH) ₁₃ .CO ₃ .3.5H ₂ O (ii), 4MgCAI ₂ O ₃ .CO ₂ .9H ₂ O (iii), 4MgCAI ₂ O ₃ .CO ₂ .6H ₂ O, ZnO.3MgO.AI ₂ O ₃ .CO ₂ .8-9H ₂ O and ZnO.3MgO.AI ₂ O ₃ -CO ₂ . 5-6H ₂ O. Special preference is given to types i, ii and iii.

Zeolites (alkali and alkaline earth aluminosilicates)

These can be described by general formula (VIII)

M _x /n [(AIO _2)X (SiO ₂ ) _y ].wH ₂ O(VIII) wherein n is the charge of the cation M;

• M is an element of Group I or Group II, such as Li, Na, K, Mg, Ca, Sr or Ba;

• y:x is a number from 0.8 to 15, preferably from 0.8 to 1.2; and

• w is a number from O to 300, preferably from 0.5 to 30.

Examples of zeolites are sodium aluminosilicates of the formulae Na ₁₂ Al ₁₂ Si ₁₂ O ₄₈ . 27 H ₂ O [zeolite A], Na ₆ Al ₆ Si ₆ O ₂₄ . 2 NaX. 7.5 H ₂ O, X=OH, halogen, CIO ₄ [sodalite]; Na ₆ Al ₆ Si ₃₀ O ₇₂ . 24 H ₂ O; Na ₈ Al ₈ Si ₄₀ O ₉₆ . 24 H ₂ O; Na ₁₆ Al ₁₆ Si ₂₄ Oso-16 H ₂ O; Na ₁₆ Al ₁₆ Si ₃₂ O ₉₆ .16 H ₂ O; Na ₅₆ Al ₅₆ Si ₁₃₆ O ₃₈₄ . 250 H ₂ O [zeolite Y], Na ₈₆ Al ₈₆ Si ₁₀₆ O ₃₈₄ . 264 H ₂ O [zeolite X];

• or the zeolites that can be formed by partial or complete replacement of the Na atoms by Li, K, Mg, Ca, Sr or Zn atoms, such as

• (Na ₁ K) ₁₀ Al ₁₀ Si ₂₂ O ₆₄ . 20 H ₂ O; Ca ₄ .5 Na ₃ [(AIO ₂₎₁₂ (SiO ₂ ) ₁₂ ]. 30 H ₂ O; K ₉ Na ₃ [(AIO ₂ J ₁₂ (SiO ₂ ) ₁₂ ]. 27 H ₂ O.

Preferred zeolites correspond to the formulae

• Na ₁₂ Al ₁₂ Si ₁₂ O ₄₈ . 27 H ₂ O [zeolite A],

• Na ₆ Al ₆ Si ₆ O ₂₄ . 2NaX. 7.5 H ₂ O ₁ X=OH, Cl, CIO ₄ , 1/2CO ₃ [sodalite]

• Na ₆ Al ₆ Si ₃₀ O ₇₂ .24 H ₂ O,

• Na ₈ Al ₈ Si ₄₀ O ₉₆ .24 H ₂ O,

• Na ₁₆ AI ₁₆ Si ₂₄ O ₈₀ .16 H ₂ O,

• Na ₁₆ Al ₁₆ Si ₃₂ O ₉₆ .16 H ₂ O,

• Na ₅₆ Al ₅₆ Si ₁₃₆ O ₃₈₄ . 250 H ₂ O [zeolite Y]

• Na ₈₆ Al ₈₆ Si ₁₀₆ O ₃₈₄ . 264 H ₂ O [zeolite X]

• and zeolites of the X od Y type possessing an Al/Si ratio of about 1 :1 , β or the zeolites that can be formed by partial or complete replacement of the

Na atoms by Li, K, Mg, Ca, Sr, Ba or Zn atoms, such as . (Na ₁ K) ₁₀ Al ₁₀ Si ₂₂ O ₆₄ . 20 H ₂ O . Ca ₄ ,5 Na ₃ [(AIO ₂ ) ₁₂ (SiO ₂ ) ₁₂ ]. 30 H ₂ O . K ₉ Na ₃ [(AIO ₂₎₁₂ (SiO ₂ ) ₁₂ ]. 27 H ₂ O

The zeolites listed may also have a lower water content or may be anhydrous. Other suitable zeolites are:

• Na ₂ 0.Al ₂ O ₃ .(2 to 5) SiO ₂ .(3.5 to 10) H ₂ 0 [zeolite P]

• Na ₂ 0.Al ₂ O ₃ .2 SiO ₂ .(3.5-10)H ₂ 0 (zeolite MAP)

• or the zeolites that can be formed by partial or complete replacement of the Na atoms by Li, K or H atoms, such as

• (Li ₁ Na ₁ K ₁ H) ₁₀ Al ₁₀ Si ₂₂ O ₆₄ . 20 H ₂ O

• K ₉ Na ₃ [(AIO ₂ ) ₁₂ (SiO ₂ ) ₁₂ ]. 27 H ₂ O

• K ₄ Al ₄ Si ₄ O ₁₆ .6 H ₂ O [zeolite K-F]

Na ₈ Al ₈ Si ₄₀ O ₉₆ .24 H ₂ O zeolite D, as described in Barrer et al., J. Chem. Soc. 1952,1561-1571, and in U.S. Pat. No. 2,950,952; The following zeolites are also suitable:

• potassium offretite, as described in EP-A-400 961 ;

• zeolite R ₁ as described in GB 841 812;

• zeolite LZ-217, as described in U.S. Pat. No. 4,503,023;

• Ca-free zeolite LZ-218, as described in U.S. Pat. No. 4,333,859;

• zeolite T ₁ zeolite LZ-220, as described in U.S. Pat. No. 4,503,023;

• Na ₃ K ₆ Al ₉ Si ₂₇ O ₇₂ .21 H ₂ O [zeolite L];

• zeolite LZ-211 , as described in U.S. Pat. No. 4,503,023;

• zeolite LZ-212, as described in U.S. Pat. No. 4,503,023;

• zeolite O, zeolite LZ-217, as described in U.S. Pat. No. 4,503,023;

• zeolite LZ-219, as described in U.S. Pat. No. 4,503,023;

• zeolite Rho, zeolite LZ-214, as described in U.S. Pat. No. 4,503,023;

• zeolite ZK-19, as described in Am. Mineral. 54 1607 (1969);

« zeolite W (K-M), as described in Barrer et al., J. Chem. Soc. 1956, 2882;

• Na ₃₀ Al ₃₀ Si ₆₆ O ₁₉₂ .98 H ₂ O [zeolite ZK-5, zeolite Q].

Special preference is given to the use of zeolite P types of formula I wherein x is from 2 to 5 and y is from 3.5 to 10, especially zeolite MAP of formula I wherein x is 2 and y is from 3.5 to 10, and very especially zeolite Na-P, that is to say M is Na. That zeolite generally occurs in variants Na-P-1 , Na-P-2 and Na-P-3, which are differentiated by their cubic, tetragonal or orthorhombic structure (R. M. Barrer, B. M. Munday, J.Chem.Soc. A 1971 , 2909-2914). The literature just mentioned also describes the preparation of zeolite P- 1 and P-2. According to that publication, zeolite P-3 is very rare and is therefore of little practical interest. The structure of zeolite P- 1 corresponds to the gismondite structure known from the above-mentioned Atlas of Zeolite Structures. In more recent literature (EP-A 384 070) a distinction is made between cubic (zeolite B or P ₀₎ and tetragonal (zeolite P ₁₎ zeolites of the P type. That publication also mentions relatively new zeolites of the P type having ShAI ratios of less than 1.07:1. Those are zeolites designated MAP or MA-P for "Maximum Aluminium P". Depending upon the preparation process, zeolite P may contain small quantities of other zeolites. Very pure zeolite P has been described in WO 94/26662.

Within the scope of the invention it is also possible to use finely particulate, water- insoluble sodium aluminosilicates which have been precipitated and crystallised in the presence of water-soluble inorganic or organic dispersants. Those compounds can be introduced into the reaction mixture in any desired manner before or during the precipitation and/or the crystallisation.

Sodium zeolite A and sodium zeolite P are very especially preferred.

The hydrotalcites and/or zeolites can be used in amounts of, for example, from 0.1 to 10 parts by weight, based on 100 parts by weight of halogen-containing polymer.

Alkali aluminocarbonates (dawsonites) These are compounds of the formula

. ((M ₂ O) _m .(AI ₂ O ₃ ) _n .Z _o .pH ₂ O},

wherein M is H, Li, Na, K, Mg-ι/2, CB^I2, Sr-,/2 or Zrii/2 ; Z is CO ₂ , SO ₂ , (Cl ₂ 0 _/ ^/2, B ₄ O ₆ , S ₂ O ₂ (thiosulfate) or C ₂ O ₂ (oxalate): m is a number from 1 to 2 when M is Mgi/2 or Cai/2, and in all other cases is a number from 1 to 3; n is a number from 1 to 4; o is a number from 2 to 4; and p is a number from 0 to 30.

The alumino salt compounds of formula (I) that can be used according to the invention may be naturally occurring minerals or synthetically prepared compounds. The metals may partially replace one another. The mentioned alumino salt compounds are crystalline, partially crystalline or amorphous or may be present in the form of a dried gel. The alumino salt compounds may also be present in relatively rare crystalline modifications. A process for the preparation of such compounds is described in EP 394 670. Examples of naturally occurring alumino salt compounds are indigirite, tunisite, aluminohydrocalcite, para-aluminohydrocalcite, strontiodresserite and hydrostrontiodresserite. Other examples of alumino salt compounds are potassium aluminocarbonate ((K ₂ O).(AI ₂ O ₃₎ .(CO ₂₎₂ .2H ₂ O}, sodium aluminothiosulfate ((Na ₂ O)-(AI ₂ O ₃₎ .(S ₂ O ₂₎₂ .2H ₂ O}, potassium aluminosulfite ((K ₂ O).(AI ₂ O ₃₎ .(SO ₂₎₂ .2H ₂ O}, calcium aluminooxalate ((CaO) ₁ (AI ₂ O ₃₎ .(C ₂ O ₂₎₂ .5H ₂ O}, magnesium aluminotetraborate ((MgO)-(AI ₂ O ₃₎ .(B ₄ O ₆₎₂ .5H ₂ O}, (([Mg ₀ .2 Na ₀ .6 ] ₂ O)-(AI ₂ O ₃₎ .(CO ₂₎₂ .4.1 H ₂ O}, {([Mgo.2 Na _o .6 ] ₂ O)-(AI ₂ O ₃₎ .(CO ₂₎₂ .4.3H ₂ 0} and {([Mg _o .3 Na _o .4 ] ₂ O)-(AI ₂ O ₃₎ .(CO ₂₎₂ .2.4.9H ₂ O}.

The mixed alumino salt compounds can be obtained in accordance with processes known per se by cation exchange, preferably from the alkali alumino salt compounds or by combined precipitation (see, for example, U.S. Pat. No. 5,055,284).

Preference is given to alumino salt compounds of the above formula wherein

• M is Na or K; Z is CO ₂ , SO ₂ or (Cl ₂ O ₇ ) ^2 ; m is 1-3; n is 1-4; o is 2-4 and p is 0-20. Z is especially CO ₂ .

Preference is given also to compounds that can be represented by the following formulae:

M ₂ 0.Al ₂ O ₃ .(CO ₂ ) ₂ . pH ₂ O (Ia) (M ₂ O) ₂ -(AI ₂ O ₃₎₂ .(CO ₂ ) ₂ .pH ₂ O(lb) M ₂ 0.(Al ₂ O ₃₎₂ .(CO ₂ ) ₂ .pH ₂ O(lc) wherein M is a metal, such as Na, K, Mg ₁ ^, Ca-ι/2, Sr-ι/2 or Zn-ι/2 and p is a number from O to 12.

Special preference is given to sodium aluminodihydroxycarbonate (DASC) and to the homologous potassium compound (DAPC).

Dawsonites may also be substituted by lithium-alumohydroxycarbonates or lithium- magnesium-alumohydroxycarbonates, as described in EP 549,340 and DE 4,425,266.

The dawsonites can be used in an amount of, for example, from 0.01 to 5, advantageously from 0.1 to 3, especially from 0.1 to 2, parts by weight, based on 100 parts by weight of halogen-containing polymer.

The stabiliser combination preferably comprises component A) and, as component B), at least one substance from the following groups: perchlorate compounds, glycidyl compounds, or dihydropyridines and polydihydropyridines.

Typical OBS' are those supplied by Chemtura Corporation under the trade mark Mark OBS™, such as Mark OBS101™ or Mark OBS113™.

The abrasives may be selected from the group including calcium carbonate, sulphate or oxide, barium sulphate, magnesium carbonate or hydroxide, silica or quartz powder, natural silicates including talc, kaolin, whether calcined or not, all the abrasives whether or not coated with silane, stearic acid or a metallic stearate.

The detergents/lubricants may be selected from a group including glyceryl esters of oleic or stearic acid, sorbitan esters of oleic or stearic acid, fatty alcohols, fatty primary or secondary amides, ethylene bis-stearamide, hydrocarbon waxes, Fischer- Tropsch waxes and polyethylene waxes (whether or not oxidised or partially oxidised).

In addition to their action as abrasives, some fillers may also be selected for their action as hydrogen chloride scavengers, and thus contribute to higher heat stability. In addition to their action as detergents, said compounds act as lubricants to modify the rheology of the purge compound and regulate the purging effect.

The purge composition would typically contain 50 to 75%, preferably 70% by mass of PVC, 5 to 10%, preferably 5 % by mass of the organic based stabiliser (OBS), 10 to 50%, preferably 25% by mass abrasives, 0% to 10%, preferably 5% by mass detergents/lubricants.

The purge composition described above is used in a method of purging of an extruder after the extrusion of a polymer, preferably PVC.

The mechanism of OBS stabilizer is to bond to the degrading PVC chain, interrupting the dehydrochlorination mechanism and preventing crosslinking, and at the same time preventing catastrophic torque increase in the extruder. Hence the purge composition can be used by PVC processors without deleterious effects on operation. The resultant purge composition is effective and compatible with PVC.

The graph in Figure 1 shows the result of temperature/torque in a Brabender Torque Test carried out on a PVC composition stabilized with 2.5% of tribasic lead sulphate which is a metallic based stabilizer. It can be seen from the graph that in the Brabender Torque Test at a temperature of 20O ⁰ C, the stabilizer begins to fail after 15 minutes and has failed within 18 minutes. In contrast, and with reference to the graph in Figure 2, a PVC composition stabilized with 2.5% of an organic based stabilizer (in this case Mark OBS101 supplied by Chemtura Corporation) in the Brabender Torque Test remains stable at a temperature of 200 ⁰ C for greater than 30 minutes.

At the end of a polymer extrusion process, a purge compound according to the invention is fed into the extruder until purge compound begins to be expelled from the extruder and die. Purging may continue as long as required to remove any unwanted hard or charred deposits generated during the extrusion process from the extruder barrel, screw or die. The extruder is then switched off. It can take from approximately 30 to 60 minutes for the extruder to cool down from an operating temperature of 16O ⁰ C to 18O ⁰ C, to a temperature below 5O ⁰ C during which time the purge compound is under heat stress. However, because of the presence of the organic based stabilizer, the purge compound of the invention does not decompose.

In the event the purge compound is required to remove any hard decomposed deposits extrusion with the purge composition continues until such time as the extrudate is clean and free of decomposed matter. The die is then removed and allowed to cool for storage until next required. The heaters on the extruder barrel are switched off; and the extruder is allowed to cool with the purge compound remaining in the barrel. If the barrel is to be further cleaned or the screw replaced in the barrel, extrusion may continue until such time as the extruder temperature is low enough that the purge compound exits the end of the barrel as a powder, thus facilitating easier removal and cleaning.

A particular advantage of the purge compound and method of the invention is that the purge may be left in the extruder awaiting a subsequent extrusion process. In the subsequent extrusion process, when the extruder is started up, the purge compound is heated, but again because it is stabilized it does not decompose. The purge compound is expelled from the extruder and regular extrusion can continue. The purge compound of the invention is more stable than purge compounds that make use of metallic based stabilizers and can reduce the down-time of an extrusion apparatus by more than half.

The invention will now be described in full with reference to the following non-limiting examples:

EXAMPLES

The purge compound according to the invention may be supplied in extruder ready fully formulated form, or as a concentrate for mixing with PVC in the converter's own equipment prior to use. In the fully formulated form the PVC powder is added to a high speed internal mixer, and the mixer is switched on. The stabiliser, fillers, and detergents are added and mixing continues until the mix reaches around 50 ⁰ C. The mix is then mixed at slow speed until the temperature reduces to below 4O ⁰ C before packing off. The converter can add the purge compound directly to the extruder.

For a concentrate, mixing proceeds exactly as above except that no PVC is added. The converter adds PVC to a high speed internal mixer, then adds the desired amount of concentrate and mixes as before. In this way the converter can add the required amount of abrasiveness to suit the specific purging requirement.

In the Examples the OBS is Mark OBS101™ supplied by Chemtura Corporation. Percentages are percentage by mass of the composition.

Example 1 - Standard Purge compound PVC 73%

Calcium carbonate 20% OBS 6%

Fischer Tropsch wax 1%

Example 2 - High stability purge for aggressive machines

PVC 70%

Calcium carbonate 20% OBS 10%

Fischer Tropsch wax 2%

Example 3 - High abrasive purge compound for tough machine deposits

PVC 72%

Calcium carbonate 15%

Silica 5%

OBS 6%

Polyethylene wax 2%

Example 4 - Standard Purge concentrate Calcium carbonate 74% OBS 22%

Fischer Tropsch wax 4%

Example 5 - High stability concentrate for aggressive machines Calcium carbonate 63% OBS 31%

Fischer Tropsch wax 6%

Example 6 - High abrasive purge concentrate for tough machine deposits Calcium carbonate 54% Silica 18%

OBS 21%

Polyethylene wax 7%